Lets review the facts.I hardly would have called myself hardcore, no where close, but I found the content just as accessible to be frank. In terms of difficulty, the game back then really was not any harder than it is now, especially when thinking about the current Heroic Modes. You claim that the current user base would not tolerate such an 'exclusive' model now, but the current feedback and subscriber numbers seem to indicate something completely different than what you are suggesting, even though this is a very simplified view of the state of the game and subscriber numbers, it is still relevant to your claims.
1. Subs are falling moderately
2. People complain (but they always complain)
3. Blizzard is targeting accessibility since cata launch when they tried hard heroics
The theory I subscribe to is that current sub decrease is due to the fact the game is old, and there isn't as many new players joining. Blizzard seems to agree and they are increasing the accessibility and levelling experience in an attempt to mitigate sub loss.
Now with regards to your personal experiences, if you feel that BC was just as easy (a measurement of difficulty) then it probable that you are not the group that Blizzard is targeting. One of the biggest challenges in WOW (and this is a form of difficulty) is to find coop content. In BC, if you managed to get into a guild that suited your style, timing and progression you are probably a lucky person. There were many people that did not find such a thing. I personally knew many guilds who were so deprived of content that they never ever managed to clear a single 5man heroic in BC. They spent their times in their daily 10 quests and raising alts. This was serious deprivation and no such player will ever consent to such an experience again.
LFD was literally a divine gift. The chances of finding a group in /2 in combination with people leaving before and during the run was extremely low. Someone leaving halfway for whatever reason meant a saved failed run. Spamming in /2 was a sign of desperation and no one wanted reasonably geared characters. They wanted FULL TIER 6 BADGE GEAR characters to run with. It doesn't matter if you slowly acquired every possible upgrade before 5heroics and were in full dungeon set. They didn't want you. Its not just the time to find a /2 spam party, its the ability to find replacements, the power to avoid elitist snobs and the the party not breaking down into a fail heroic saved run. All of this was worth far more than 20min. Some would even say its worth more than 120min. At the very least.
LFR was another divine gift. Do you know how many players have never ever seen the inside of a raid? Or actually made it past the first 2-3 bosses from one of the regular PUGs? Blizzard does. And they wisely decided that it was too many players. They understand that not everyone has a raiding guild or the time to bang their head against the wall in wipefests. They wisely decided that it is better to allow such players to see content than to leave them with only the new LFD to play with. (Or worse, before WOTLK's LFD there was only dailies/alts for the non PVP players). A player with a raiding guild may never be able to understand the emotion involved in finally seeing deathwing in LFR. I know of players who saw they're first ever raid content there in dragon's soul. Having been put off even 5man heroics by the pre end of time 5mans.
Cross realm coop is another really good thing they did. I made so many xrealm friends, I'm truly glad this existed. Every 5man heroic run is a joy. Its either i'm truly lucky or somehow i convince trolls to play nice.
WOW in pandaland is arguably the most accessible ever. I love it to hell and back. Yes i've been unsubbed for a bit but I would recommend it heartily to many and recently with a 7day free mail coupon, I see its as amazingly fun and accessible as ever. There is no middle ground. There is only more and more accessibility until Blizzard decides to change course. You think the above changes are too much? You haven't seen nothing yet. Look at what is on the horizon or recently done in pandalandLastly, Blizzard has targeted accessibility over good engaging content, and I don't care how much you pretend to say that such accessible content is engaging because in it's current format it isn't, people play and then they leave quite fast because of how accessible it is. So if we're not the target audience and we leave, the people who stay eventually leave to, because that is what is happening right now, it's a cascade effect. There is a middle ground to be met, somewhere between TBC and WotLK, but Blizzard horrible overshot the mark or didn't want the game to go there at all (due to the vocal player feedback), and the game has been steadily declining since then.
PVP is targeted as a place that isn't accessible. They impose an ilvl ceiling. They increase the ease of gearing. There's probably quite a bit more they can do to make it more accessible too.
LFR is targeted as a place that isn't accessible enough. You get a stacking buff when you wipe now. Its a pretty powerful buff too at 5% a stack. Any boss that causes too many wipes gets pounded by the nerfbat. There's a lot more they can do as well.
The levelling curve is probably the next on their list but the direction is clear. Accessibility is the goal. Exclusiveness is not what they want but they'll occasionally throw a bone to the elitist like having achievements for prenerf content.